Narrative:At 7000 feet, when descending towards Hill AFB, the crew got a no. 2 prop low oil warning. The engine was shut down, but the prop wouldn't feather. An emergency was declared and the aircraft landed on runway 32. During the ground roll, the no. 2 prop separated. Pieces ruptured the no. 1 fuel tank. This caused an explosion and a fire on the left side of the Electra. The aircraft came to rest 4000 feet from the runway threshold.